Work around IGDs that deduplicate entries based on the internal port

This is a violation of the UPnP IGD specification but we can relay through an alternate port as a workaround.

miss/miss.vcxproj.filters

@@ -24,6 +24,9 @@
     <ClCompile Include="pcp.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="relay.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <ResourceCompile Include="miss.rc">
@@ -34,5 +37,8 @@
     <ClInclude Include="..\version.h">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="relay.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
   </ItemGroup>
 </Project>